1. Field
This invention relates generally to a helical antenna and, more particularly, to a helical antenna that can be folded both axially and radially into a compact configuration suitable to be stowed on and deployed from a nano-satellite.
2. Discussion
Satellites orbiting the Earth, and other spacecraft, have many purposes, and come in a variety shapes and sizes. One known satellite type is referred to as a cubed nano-satellite (cubesat) that is typically used solely for communications purposes. Cubesats are modular structures where each module (1U) has a dimension of 10 cm×10 cm×10 cm, and where two or more of the modules can be attached together to provide satellites for different uses.
Satellites typically employ various types of structures, such as reflectors, antenna arrays, ground planes, sensors, etc., that are confined within a stowed orientation into the satellite envelope or fairing during launch, and then unfolded or deployed into the useable position once the satellite is in orbit. For example, satellites may require one or more antennas that have a size and configuration suitable for the frequency band used by the satellite. Cubesats typically operate in the VHF or UHF bands. Because cubesats are limited in size, their antennas are required to also be of a small size, especially when in the stowed position for launch. Cubesats have typically been limited to using dipole antennas having the appropriate size for the particular frequency band being used. However, other types of antennas, such as helical antennas, have a larger size, and as thus offer greater signal gain, which requires less signal power for use.
It is known in the art to deploy helical antennas on various types of satellites other than cubesats. Known satellites that employ helical antennas typically have been of a large enough size where the antenna can readily be stowed in a reduced area for launch. However, these helical antennas have typically been confined only in an axial direction, i.e., in a lengthwise direction, for subsequent deployment. For a cubesat, this level of confinement and reduced size for stowing of a helical antenna is unsatisfactory.